The present invention relates to a resin-encapsulated type semiconductor integrated circuit device in which integrated circuit chips are mounted on both surfaces of a chip mounting section of a lead frame and the electrodes and the lead terminals of these integrated circuit chips are connected together by bonding wires.
The resin-encapsulated type semiconductor integrated circuit device has a construction in which an integrated circuit chip is mounted on a chip mounting section of a lead frame and the electrodes and the lead terminals of this integrated circuit chip are connected together by bonding wires. In an attempt at improving the functions or mounting density of such a normal resin-encapsulated type semiconductor integrated circuit device, there has been proposed a dual-surface mounting type semiconductor integrated circuit device having a construction in which integrated circuit chips are mounted on both surfaces of a chip mounting section of a lead frame.
FIG. 10 shows a schematic diagram of a prior art dual-surface mounting type semiconductor integrated circuit device. In the figure, the reference numeral 71 denotes a chip mounting section of a lead frame, and integrated circuit chips 72 and 73 are mounted on both its surfaces. Electrodes (not shown) of the integrated circuit chips 72 and 73 are connected to lead terminals 74 by bonding wires 75. The reference numeral 76 denotes an encapsulation resin for encapsulating the integrated circuit chips 72 and 73 and the bonding wires 75. For example, when the integrated circuit chips 72 and 73 are memory chips having identical capacities and a double capacity is provided by dual-surface mounting, there can be obtained a semiconductor integrated circuit device whose function (capacity) is doubled although it is identical in terms of area by mounting two memory chips which differ from each other only in their decoder circuit portions for outputting a selection signal to the internal circuits based on a chip selection signal input and have identical constructions of the other portions on both the surfaces of the chip mounting section (note that one chip has a laterally (or vertically) inverted structure relative to the other chip) and connecting the corresponding electrodes of the memory chips to an identical lead terminal. Such a semiconductor integrated circuit device is disclosed in, for example, the document of Japanese Patent Laid-Open Publication No. HEI 2-87661.
However, the above prior art dual-surface mounting type semiconductor integrated circuit device has the following problems.
That is, the above prior art dual-surface mounting type semiconductor integrated circuit device has the problem that the circuits of the two integrated circuit chips wastefully overlap each other, i.e., the problem that both the integrated circuit chips sometimes individually have a circuit for implementing a mutually identical function, causing a waste in terms of chip area or consumption power in the case.